Effects of cell number on teratoma formation by human embryonic stem cells

Abstract

Teratoma formation is a critical obstacle to safe clinical translation of human embryonic stem (ES) cell-based therapies in the future. As current methods of isolation are unable to yield 100% pure population of differentiated cells from a pluripotent donor source, potential development of these tumors is a significant concern. Here we used non-invasive reporter gene imaging to investigate the relationship between human ES cell number and teratoma formation in a xenogenic model of ES cell transplantation. Human ES cells (H9 line) were stably transduced with a double fusion (DF) reporter construct containing firefly luciferase and enhanced green fluorescent protein (Fluc-eGFP) driven by a human ubiquitin promoter. Immunodeficient mice received intramyocardial (n = 35) or skeletal muscle (n = 35) injection of 1 x 10 2 , 1 x 10 3 , 1 x 10 4 , 1 x 10 5 or 1 x 10 6 DF positive ES cells suspended in saline for myocardium and Matrigel for skeletal muscle. Cell survival and proliferation were monitored via bioluminescence imaging (BLI) for an 8 week period following transplantation. Mice negative for Fluc signal after 8 weeks were followed out to day 365 to confirm tumor absence. Significantly, in this study, a minimum of 1 x 10 5 ES cells in the myocardium and 1 x 10 4 cells in the skeletal muscle was observed to be requisite for teratoma development, suggesting that human ES cell number may be a critical factor in teratoma formation. Engraftment and tumor occurrence were also observed to be highly dependent on ES cell number. We anticipate these results should yield useful insights to the safe and reliable application of human ES cell derivatives in the clinic.

Prospective isolation of human embryonic stem cell-derived cardiovascular progenitors that integrate into human fetal heart tissue

“…A major concern f/f0 (a.u.) is their capacity to from teratomas after transplantation (32). The progenitor population we isolated based on the expression of distinct surface markers did not form teratomas when transplanted into mouse or human hearts.…”

Enhancement of Striatal Dopaminergic Function Following Autologous Neural Cell Ecosystems (ANCE) Transplantation in a Non-Human Primate Model of Parkinson’s Disease

“…The large amount of donor fetal tissues, immunosuppressive drugs and graftinduced side-effects are some of the limitations associated with the use of fetal midbrain tissues [18,19]. Moreover, embryonic stem cell engraftment raises the issue of tumor formation due to uncontrolled cellular proliferation and ethical controversies [20,21]. Recently, the induced pluripotent stem cell approach showed positive outcomes in NHP MPTP model but these positive results still need to be confirmed [22].…”

Potential antitumor therapeutic strategies of human amniotic membrane and amniotic fluid-derived stem cells

“…However, they are currently facing major limitations for use. Some investigations have described the tumorigenicity of undifferentiated hESCs 7 and the possibility of teratoma formation when injected directly into other bodies. 8 Moreover, the procedures used to collect hESCs from human embryos are associated with substantial moral and ethical issues.…”